The present invention provides a novel stable oil-in-water microemulsion cosmetic composition. An oil-in-water microemulsion cosmetic composition according to the present invention contains: a dispersion medium which contains water and a divalent glycol； an oil component which is dispersed in the dispersion medium, while containing a silicone oil and a hydrocarbon oil； a carboxyl-modified silicone surfactant represented by formula 1； at least one compound which is in a liquid state at 25DEG C and has 16-22 carbon atoms, and which is selected from among higher alcohols and higher fatty acids； and a nonionic surfactant which has a polyoxyethylene chain, while having an HLB of 12-17. This oil-in-water microemulsion cosmetic composition is configured such that the average particle diameter of oil droplets is 150 nm or less. In formula 1, at least one of R1-R3 moieties is expressed by -O-Si(R4)3 wherein R4 represents at least one substituent selected from among alkyl groups having 1-6 carbon atoms and a phenyl group； in cases where not all of the R1-R3 moieties are the substituents, the rest may be the same or different and each represents a substituted or unsubstituted monovalent hydrocarbon group； A represents a linear or branched alkylene group which is represented by CqH2q wherein q represents an integer of 0-20； and M represents a metal atom or an organic cation.本發明提供一種穩定且新穎之水中油滴型之微細乳液型化妝料。本發明之水中油滴型之微細乳液型化妝料含有：包含水及二元醇之分散介質、分散於該分散介質中且包含聚矽氧油及烴油之油分、下述式1所表示之羧基改性聚矽氧系界面活性劑、於25℃下為液狀且碳原子數為16～22之選自高級醇及高級脂肪酸中之至少一種、以及具有聚氧乙烯鏈且HLB為12～17之非離子性界面活性劑，且油滴之平均粒徑為150 nm以下，式1中，R1～R3中之至少1個為以-O-Si(R4)3表示且R4為選自碳原子數1～6之烷基及苯基中之至少一種之取代基，於R1～R3不全部為上述取代基之情形時，其餘為可相同或不同之未取代或取代型之一價烴基，A為以CqH2q表示且q為0～20之整數之直鏈狀或支鏈狀之伸烷基，且M為金屬原子或有機陽離子。
